When C58 mice are immunized to syngeneic malignant lymphocytes (Ib cells) they develop an age dependent autoimmune disease designated "immune polioencephalomyelitis" or IPE. We are developing this disease syndrome as a model, in the mouse, of age related autoimmune diseases in man, particularly those of the CNS. Experiments are in progress to identify the inductive aspects of the disease, viz, route and dose of antigen, strain specificity of mice, incidence of disease in x-ray or drug immunosuppressed mice, etc. Studies also are in progress to identify the efferent aspects of the disease, viz, whether B, T or macrophage cells are cytotoxic and whether neurons per se, their supportive tissues, are the primary target cells.